Process of producting multicolor photographic images in a single emulsion layer



J n 22, 19 8- w. T. HANSON, JR., ETAL 2,443,909

PROCESS OF PRODUCING MULTICOLOR PHOTOGRAPHIC IMAGES IN A SINGLE EMULSION LAYER Fi led June 28, 1946 EXPOSED THROUGH RED JEPARAT/OH /MAGE AND cYA/y DEVELOPED.

ELAGHED AND, COLOR DEVELOPED 7'0 FORM SOLUBLE DYE.

s/L VER RECONVERTED To G/L l/ER HAL/DE.

MAGENTA EXPOSED THROUGH GREEN GEPARAT/O/Y /4 DYE IMAGE AND MAGENTA DEVELOPED.

FLASHED AND COLOR DEVELOPED TO FORM SOL UBLE DYE.

SILVER RECON VERTED TD S/Ll/ER YELLOW ExPosED THROUGH BLUE GEPARAT/O/Y /MA6E YELLOW DEVELOPED, AND

G/L VER REMOVED.

V h eG/ey 7.770/750/7J/t A Thomas H. Farrel/ ILVZE TORs ORNEY 'ATT Patented June 22, 1948 PROCESS OF PRODUCING MULTICOLOR PHOTOGRAPHIC IMAGES IN A SINGLE EMULSION LAYER Wesley T. Hanson, Jr., and Thomas H. Farrell, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application June 28, 1946, Serial No. 679,890

.The present invention relates to color photography and particularly to a method for forming multi-color images in a single photographic emulsion layer.

The formation of multi-color images by color development in a multi-layer photographic material is well known and it has also been proposed to form images of a single color in a single emulsion layer by color development. The formation of multi-color images in a single emulsion layer by color development has also been suggestedbut such methods have generally not been successful unless the color-forming or coupling components are incorporated in the emulsion layer, as in the mixed grain methods.

It is therefore an object of the present invention to provide a method for the formation of multi-color images in a single silver halide emulsion layerby color development. Other objects will appear from the following description of our invention.

These objects are accomplished according to the method more fully described hereinafter, an essential feature of. which is the successive exposure of the emulsion layer to color separation images followed by development of the residual silver halide in a color developer forming a soluble dye and rehalogenization of all of the developed silver.

The accompanying drawing is a series of sectional views of film at various stages in the process according to our invention.

As stated above, our method enables the forma tion of a multi-color photographic image, for example, an image in three colors, in a normal silver halide emulsion layer. This layer is successively exposed to light under the images which are to be recorded and if a natural color image is to be formed, it is customary to use color separation negatives for this purpose. The negatives are registered in some suitable way and after each exposure, the film is developed in a color-forming developer suitable for the formation of an image representing the particular color separation-negative to which the film has been exposed. After each exposure step except the last, the film is developed in. a color-forming developer followed by a flash exposure and development in a color-forming developer which produces a soluble dye image. The soluble dye is washed from the layer and the silver images are then rehalogenized and, if necessary, resensitized before the next exposure. After the last exposure to a color separation negative, the silver images are removed in the usual way. This 3 Claims. (c1. 95-2) process will be more readily understood by reference to the following description of a method of forming a natural-color picture in an emulsion layer. A film having a normal positive silver halide emulsion is treated according to the following procedure:

(1) Expose through a red separation negative.

(2) Develop ford minutes in a solution of the following composition which forms a cyan image:

Grams Z-amino-E-diethylamino toluene hydrochloride 2.5 Sodium sulfite 20 Sodium carbonate 20 Potassium bromide 2 fi-nitro-benzimidazole .03 Sodium thiocyanate .5 Sodium hydroxide .5 2,4-dichloro-a-naphthol 1 Water to 1 liter (3) Wash 3 minutes in water. (4) Flash exposure sufficiently to totally expose residual silver halide.

Resorcinol .5 Water to 1 liter (6) Wash 3 minutes in water.

(7) Treat for 6 minutes in the following solution which converts all silver to silver bromidef 5 grams per liter of potassium dichromate 40 grams per literof potassium alum and 20 grams per liter of potassium bromide in a solution adjusted with sulfuric acid to a pH of (8) Wash 6 minutes in water.

(9) Resensitize by treating the film for two minutes in a solution containing 5 grams per liter of sodium bisulfite.

(10) Wash 3 minutes with water.

(11) Dry (or this step may be omitted).

(12) Register and expose film through green separation negative. :f

(13) Develop 6 minutes in the following solution which produces a magenta image:

Grams 2-amino-5-diethylamino toluene hydro chloride 2.5 Sodium sulfite 20 Sodium carbonate 20 Potassium bromide 2. G-nitro-benzimidazole .03 Sodium thiocyanate ".5 Sodium hydroxide .5 1-ph'enyl-3-methy1-5-pyrazolone 3 Elon 0.1

Water to 1 liter Repeat steps 3 through 11.

(14) Register and expose through blue separation negative.

(15) Develop for 9 minutes in the following Water to 1 liter.

(16) Bleach the silver image in the following solution:

Grams Potassium ferricyanide 10 Potassium bromide Water to 250 cc.

(1'!) Fix in a 30% solution of hypo.

(18) Wash.

(19) Dry.

One of the important features of our process is the use of a color developer for complete development of the non-image-forming grains. This developer, composed of the same developing agent as the color developer and of resorcinol as a coupler. forms a water-soluble dye image and develops the non-image residual silver halide to the same state as the image-forming color developer so that after rehalogenizing, the film is composed of a dye image plus a rehalogenized emulsion of uniform sensitivity characteristics. Omission of this developer leaves the grains which were used in forming the first color image in a very different state from the residual grains so that the successive exposures to the other separation images are not independent of the first image present, as they should be.

The coupling agents used to form the colored images may be any of the well known coupling agents such as those described in U. S. Patents 2,039,730, 2,313,586. 2,362,598, reissue 22,329, 1,969,479, 2,343,703, 2,108,602, 2,271,238- and 2,364,675. The developing agents may be any of those well known in the color development art and the same developing agent need not be used for both the image-forming development and the development of the soluble dye. It is preferable however, that these developing agents be similar so that the silver images produced in different parts of the layer are similar.

In place of resorcinol, other couplers capable of forming soluble dye images may be used such as 1,3-dihydroxy-4-chlorobenzene, 2,4 dihydroxy boxylic acid, 1-p-sulfophenyl-B-methyl-5-.pyrazolone, l-p-sulfophenyl 5 pyrazolone 3 carboxylic acid, 3,5-diaminobenzoic acid, 1,3,5-triaminobenzene, 2,4,6-triaminobenzoic acid, 2,4,6- triaminochlorobenzene, diethylmalonate, barbituric acid, etc.

Our invention will be further illustrated by reference to the accompanying drawing.

A sensitive photographic element comprising a support having thereon a silver halide emulsion layer Ill as shown in step 1 of the drawing is exposed through a red separation negative image and developed in a developing solution which produces a cyan image. This forms a cyan image H in emulsion layer W as shown in step 2 of the drawing and leaves undeveloped silver halide in the unexposed portions of the emulsion layer. The film is then flashed to fully expose the residual silver halide and color developed in a solution containing resorcinol or other coupler which produces a soluble dye image and metallic silver I! as shown in step 3 of the drawing. The silver image in the region of the cyan dye image H and the silver image l2 are then converted to silver halide I3 as shown in step 4 of the drawing. Since both regions of the layer have been developed in a color-forming developer and reconverted to silver halide in the same bath, the silver halide in the entire emulsion layer is now uniformly light-sensitive.

The emulsion layer is then exposed through a green separation negative image in register with the first exposure and the emulsion layeris developed in a color-forming developer which produces a magenta image M in the emulsion layer. The image 14 may coincide partially or completely with the cyan image or may be in a separate re-' gion of the emulsion layer. It is entirely inde: pendent of the cyan image previously formed in the layer.

The emulsion layer is again flashed with light which uniformly exposes the residual silver halide and again color developed in a color developer containing resorcinol or other coupler which produces a soluble dye image in the residual halide of the emulsion layer and metallic silver l5 as shown in step 6 of the drawing. The silver is again converted to silver halide as shown as H5 in step '7 of the drawing and is thereby rendered uniformly light-sensitive as before.

The emulsion layer is then exposed through the blue separation negative image in register with the cyan and magenta images previously formed in the layer and developed in a yellow color-forming developer to form the yellow image I! as shown in step 8 of the drawing. The silver images are then removed leaving the cyan, magenta and yellow images ll, l4 and IT in the emulsion layer.

It will be understood that the examples and modifications described herein are illustrative only and that our invention is to be taken as limited only by the scope of the appended claims.

We claim:

1. The process of color photography which comprises exposing a silver halide emulsion layer toa color component image, developing the layer in a color-forming developer which forms a silver and insoluble dye image, uniformly exposing said layer and developing all residual silver halide in a color-forming developer of substan tially the same composition and containing the same developing agent as said first-mentioned developer, which forms a silver and soluble dye image, Washing the soluble dye from the layer, rehalogenizing all developed silver to silver halide, and repeating the steps of exposure to a color component image and development in a color-forming developer forming an insoluble dye image with at least one other color component image, and removing all developed silver images from the layer.

2. The process of color photography which comprises exposing a silver halide emulsion layer to a color component image, developing the layer in a color-forming developer which forms a silver and insoluble cyan dye image, uniformly exposing said layer and developing all residual silver halide in a color-forming developer of substantially the same composition and containing the same developing agent as said first-mentioned developer, which forms a silver and soluble dye image, washing the soluble dye from the layer, rehalogenizing all developed silver to silver halide, exposing the layer to a second color component image in register with the first image,

3. The process or color photography which comprises exposing a silver halide emulsion layer to a red color component image, developing the layer in a color-forming developer which forms a silver and insoluble cyan dye image, uniformly exposing said layer and developing all residual silver halide in a color-forming developer which contains resoncinol as a coupler which has substantially the same composition and contains the same developing agent as said first-mentioned developer, and which forms a silver and soluble dye image, washing the soluble dye from the layer, rehalogenizing all developed silver to silver halide, exposing the layer to a green color component image, developing the layer in a colorforming developer which forms a silver and insoluble magenta dye image, uniformly exposing said layer and developing all residual silver haldeveloping the layer in a color-forming developer which forms silver and insoluble magenta dye image, uniformly exposing said layer and developing all residual silver halide in a colorforming developer of substantially the same composition and containing the same developing agent as said first-mentioned developer, which forms a silver and soluble dye image, washing the soluble dye from the layer, rehalogenizing all developed silver to silver halide, exposing the emulsion layer to a third color component image, developing the layer in a color-forming developer which forms a silver and insoluble yellow dye image, and removing all developed silver images from the layer.

ide in a color-forming developer which contains resorcin-ol as a coupler which has substantially the same composition and contains the same developing agent as said first-mentioned developer, and which forms a silver and soluble dye image, Washing the soluble dye from the layer, rehalogenizing all developed silver to silver halide, exposing the layer to a blue color component image, developing the layer in a color-forming developer which forms a silver and insoluble yellow dye image and removing all developed silver images from the layer.

WESLEY T. HANSON, JR.

THOMAS H. FARRELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,976,301 Seymour et a1 Oct. 9, 1934 2,210,905 Eggert et a1. Aug. 13, 1940 2,244,589 Yanket June 3, 1941 2,336,243 Hauson Dec. 7, 1943 

